To improve residence and office environments, more and more lamps are installed in rooms to give people bright indoor lighting. However, when the outdoor lighting is sufficient, or when there are fewer people in the room, or when people need to rest, people wish to have a dimmer light to save power.
But, currently, most of the switches used for controlling lamps do not have the function of regulating the light depending on demand. Although some switches have a dimming function, the operation is very complicated.